TUESDAY, Oct. 30 (HealthDay News) -- Cancer survivors' quality of life can vary widely depending on the type of cancer, and millions of U.S. cancer survivors have a lower-than-normal quality of life, a new study finds.

Researchers looked at more than 1,800 adult cancer survivors and more than 24,000 adults with no history of cancer and found that survivors of melanoma, breast and prostate cancers had a mental- and physical-health-related quality of life similar to those who never had cancer.

Survivors of cervical, blood and colorectal cancers, as well as survivors of cancers with a five-year survival rate of less than 25 percent (such as liver, lung and pancreatic cancers), however, had worse physical-health-related quality of life.

And survivors of cervical cancer and cancers with a low five-year survival rate also had worse mental-health-related quality of life, according to the study, which was published in the Oct. 30 issue of the journal Cancer Epidemiology, Biomarkers & Prevention.

The investigators found that 25 percent of cancer survivors had lower than normal physical-health-related quality of life, and 10 percent had lower than normal mental-health-related quality of life. In all, about 3.3 million U.S. cancer survivors have a below-average physical quality of life, and nearly 1.4 million have a below-average mental quality of life, the researchers estimated.

"It is very concerning that there are a substantial number of cancer survivors who experience poor mental or physical health years after cancer," study author Kathryn Weaver, assistant professor at Wake Forest Baptist Medical Center in Winston-Salem, N.C., said in a journal news release.

"Our results will serve as a baseline so that in five to 10 years, we can assess whether current approaches to improving the health and well-being of cancer survivors are having a positive effect," she said. "I also hope our data will draw attention to the ongoing needs of cancer survivors -- particularly those with cervical, blood and less common cancers -- and to the importance of monitoring these individuals, even long after their cancer diagnosis."